Various LED packages are known. For example, wafer level chip scale LED packages are known which are directly solderable on a suitable substrate. Such a package typically has two contacts to the p-n junctions of the diode. The LED package can for example be mounted to a substrate carrying control circuitry for the LED, for example ESD diodes or control transistors.
By way of example, an LED die can be mounted on a silicon substrate, in which the substrate contains an embedded ESD protection diode. Contacts on the top of the substrate makes electrical connection with the LED die terminals, and the substrate has further external contacts on the same top face, outside the area where the LED die is mounted. This requires individual placement of each LED die over the substrate, for example using a ball grid array.
It is also known that in addition to ESD protection, by associating LEDs with control transistors, it becomes possible to drive and control strings of LEDs. For example, multiple LEDs in series can be controlled individually by connecting individual FET transistors parallel to each LED. By closing a transistor switch, a corresponding LED is shorted and will be switched off.
There remains a need for a cost effective and compact packaging solution for LEDs and associated control devices (such as a transistor or ESD protection diode or more complicated control circuit).